A power converter is a power processing circuit that converts an input voltage into a specified output voltage. In many applications requiring a DC output, switched-mode DC/DC converters are frequently employed to advantage.
Unlike most of the electronics industry, the power electronics industry rarely utilizes standardized circuit configurations in design work. Whenever a converter is required, a new design is generally created. As the industry exists today, there are multitudinous converter designs in use. Any standardized circuit integration in this area could greatly benefit the establishment.
Lack of integration in converter circuits generates obstacles to standardizing circuits and parts, resulting in long design cycles. Not only is more time required to design an entire circuit, but there is also a greatly increased chance for design errors to arise. Furthermore, designs utilizing power components in discrete forms possess inherent problems not usually associated with integrated circuits.
In addition to design problems, labor-intensive assembling processes and poor manufacturability usually associated with employing discrete parts greatly increase production costs. Since there is no standardization, all assembly is accomplished manually. Human error becomes a concern as expenses increase with mistakes in assembly such as placing components in the wrong position, backwards or even in the place of another element.
Along with manufacturability improvements, increased power density is a continuing goal of modern power supply (e.g., power converter) design. High power density is particularly crucial in applications wherein the allocated space for the power supply relative to the power output is restricted. Large amounts of board area are wasted as the assembler must be able to manually manipulate the components opposed to automated construction which require less construction space and result in less assembly errors.
In addition to being highly compact, the power supply should be efficient to limit heat-creating power dissipation. To dissipate the heat generated in the power supply, typically, heat sinks are mounted on the power supply components. In such components, the power devices are usually attached to the heat sinks manually. Individual heat sinks for the discrete components of the power converter raise some concerns, namely, it creates additional costs that cannot be readily absorbed in a cost competitive market; also, it decreases the flexibility necessary to design a higher circuit density power supply.
During the past several years, there have been many efforts trying to integrate power circuits in the power electronics industry. Many power metal oxide semiconductor field-effect transistors (MOSFETs) and isolated-gate bipolar transistors (IGBTs) used in motor drive industry are integrated in one package formulating so-called power modules. Instead of dealing with multiple discrete active switches, either MOSFETs or IGBTs, designers deal with only one packaged module for a circuit. These type of modules are typically composed of the same type of active switches, and snubber circuitry is excluded.
In power supply industry, the effort has been concentrated on the integration of control, drive and power switch circuitry in one package. Power Integrations, Inc., for instance, has come up with the product family called "TOPSwitch", which integrates a power MOSFET with its associated drive and control circuit packaged in T0220, T0251, or T0252 package. See TOPSwitch Family Data Sheet, by Power Integrations, Inc. of Mountain View, Calif., June 1994. Due to limitation of power handling capability and inflexibility of the control configuration, it is limited to the low power applications.
Accordingly, what is needed in the art is an integrated power module in a standardized package that may be implemented in a high power density and high performance power supply.